Fix reserved keyword quoting in staging model column definitions

The column aliases `as database` and `as schema` in stg_nodes.sql and
stg_sources.sql cause T-SQL syntax errors since these are reserved
keywords. Use quote_identifier dispatch macro for the aliases too.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Author: sdebruyn

models/staging/graph/stg_nodes.sql

@@ -31,8 +31,8 @@ select
     cast(1 as {{ dbt.type_boolean() }}) as is_contract_enforced,
     cast(0 as {{ dbt.type_int() }}) as total_defined_columns,
     cast(0 as {{ dbt.type_int() }}) as total_described_columns,
-    cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as database,
-    cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as schema,
+    cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as {{ dbt_project_evaluator.quote_identifier('database') }},
+    cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as {{ dbt_project_evaluator.quote_identifier('schema') }},
     cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as package_name,
     cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as alias,
     cast(1 as {{ dbt.type_boolean() }}) as is_described,

models/staging/graph/stg_sources.sql

@@ -27,8 +27,8 @@ select
     cast(1 as {{ dbt.type_boolean() }}) as is_enabled,
     cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as loaded_at_field,
     cast(1 as {{ dbt.type_boolean() }}) as is_freshness_enabled,
-    cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as database,
-    cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as schema,
+    cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as {{ dbt_project_evaluator.quote_identifier('database') }},
+    cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as {{ dbt_project_evaluator.quote_identifier('schema') }},
     cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as package_name,
     cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as loader,
     cast(null as {{ dbt_project_evaluator.type_string_dpe() }}) as identifier,